Heat-developable diazotype material



United States Patent 3,416,924 HEAT-DEVELOPABLE DIAZOTYPE MATERIAL PaulJoseph Hubert Tummers, Velden, Netherlands, as-

siguor to Van der Grinten N.V., Venlo, Netherlands, a corporation ofDutch Law No Drawing. Filed Mar. 5, 1965, Ser. No. 437,595 Claimspriority, application Netherlands, Mar. 10, 1964, 6402452 8 Claims. (Cl.96-75) ABSTRACT OF THE DISCLOSURE Heat-developable diazotype materialhaving improved keeping quality and developable at temperatures below150 C. contains, with a diazo compound, an al o-coupling component andan acid-reacting stabilizer, a developing agent comprising dispersedparticles of a substantially water-insoluble salt of a polybasic acidhaving a dissociation content between 7x10" and 1x10 and an aliphaticamine of the formula R being an aliphatic hydrocarbon radical having atleast 8 C atoms, R and R each being hydrogen or an aliphatic hydrocarbonradical, and R R and R together comprising at least 16 C atoms.Especially suitable is di(octadecylammonium)oxalate present with oxalicacid in a light-sensitive layer containing a hydrophilic binder such aspolyvinyl alcohol modified by polyvinyl pyrrolidone.

The invention relates to heat-developable diazotype material whichcontains a diazo compound, an azo-coupling component, an acid-reactingcompound, and a developing agent which, upon heating, is able toneutralize an acid.

Heat-developable diazotype materials are known. As a rule, they differessentially from the known two-component diazotype materials only inthat, besides the diazo compound, the azo-coupling component, and anacid-reacting compound, they also contain the alkali required for thedevelopment. This alkali, however, has been incorporated in the materialin such a way that it only becomes active after the material has beenheated to l00200 C. The alkali may be present in the light-sensitivelayer, e.g. in a neutral, chemically combined state, e.g. in a compoundsuch as urea (which upon heating above 150 C., for instance, showsaccelerated decomposition with splitting-off of ammonia), or may beincorporated in a separate layer, which is either in contact with thelight-sensitive layer, or separated from the light-sensitive layer bymeans of a so-called intermediate layer. In the latter case thedeveloping agent may be an aliphatic amine. (See:

Kosar J., Photographic Science & Eng. 5, 239-243 (1961).) 4

The manufacture of a heat-developable multi-layer diazotype material iscumbersome and expensive, especially when use is made of non-aqueousliquids, so that such a material is considerably more expensive thancomparable two-component diazotype materials.

Heat-developable diazotype materials in which urea, or

3,416,924 Patented Dec. 17, 1968,

ICC

a similar compound which upon heating splits off -am-' monia or anamine, is employed as developing agent and in which all the componentsrequired for the formation of the azo-dyestufl? have been incorporatedin one layer, can be manufactured in a reasonably inexpensive way, butsuch materials have to be developed at temperatures of about C. if theyare to yield sufiiciently strong azo-dyestuff images. Such highdevelopment temperatures are not desirable. Moreover, these materialscannot be stabilized to the proper degree. When there is incorporated insuch a material a sufiicient quantity of an acid-reacting compound toobtain a material of good keeping quality, the material shows hardly anydevelopment. When the quantity of acid is decreased until the materialyields a sufiiciently strong azo-dyestuif image upon development, thekeeping quality of the material becomes insufiicient.

Attempts have been made to overcome this difiiculty by stabilizing suchmaterials with acids which decompose and/ or volatilize upon heating. I

British patent specification N0. 907,724 describes heatdevelopablediazotype material which, besides the diazo compound and theazo-coupling component, contains an acid which volatilizes or decomposesat elevated temperatures, as well as a developing agent which, uponheating, liberates a basic-reacting component. As suitable acidsvolatilizing or decomposing upon heating are mentioned: malonic acid,gluconic acid, cyanoacetic acid, malic acid and maleic acid. Thedeveloping agent is preferably a substance which, upon heating, splitsoff ammonia or an amine, such as urea, guanidine, and their alkylderivatives; however, it may also consist of a salt of an alkylamine,and especially of a hydroxyalkylamine, with an acid which volatilizes ordecomposes upon heating. The developing agents mentioned in the saidBritish patent specification are readily soluble in water. The diazotypematerial should be free from hygroscopic substances, such as ethylenegylcol, since these substances keep the moisture content of thelight-sensitive layer atsuch a value, or bring it to such a value, thatin the said layer a small amount of solvent for the diazo compound, theazo-coupling component, and the developing agent is always present,which results in premature formation of azp-dyestuff. (See page 1, lines61-79 of the said British patent specification.)

The diazotype material described in British patent specification No.907,724 can indeed be kept for some time if it has only a very lowmoisture content and kept in a moisture-proof package in a cool place,although even under these favourable conditions it is not very stable inconsequence of the high content of water-soluble developing agent andthe relatively low acid content. However, when it is exposed to the air,particularly when it is used for making copies, e.g. in an oflice, itabsorbs moisture from the air (particularly when the support is paper)and, notwithstanding the absence of hygroscopic substances, inconvenientpremature azo-dyestutf formation soon takes place. For this reason thediazotype material described in the said British patent specification isunsuitable in practice.

The present invention relates to heat-developable diazotype materialcontaining a diazo compound, an azo-coupling component, an acid-reactingcompound, and a developing agent which is a water-insoluble salt of'apolybasic acid having a first dissociation constant between 7X10 and1X10 and a primary, secondary, or tertiary aliphatic amine of thegeneral formula in which R; is an aliphatic hydrocarbon radical with atleast 8 carbon atoms, and R and R stand for a hydrogen atom or analiphatic hydrocarbon radical, while R R and R together carry at least16 carbon atoms, the salt containing at least two cations formed from anamine according to the above formula. The various components aredistributed over at most two layers.

Generally, the diazotype material according to the invention has muchbetter keeping quality than comparable diazotype material which containsone of the known developing agents. Moreover it can be developed attemperatures below 150 C. to yield copies showing a strong azo-dyestufiimage.

It is surprising that the salts defined above can be used as developingagents in heat-developable diazotype materials. Their solubility inwater and in the conventional acid aqueous sensitizing liquids is verylow and is generally of the order of a few milligrams, or less, per 100ml. of liquid. Moreover, the amines present in the salts are alsopractically water-insoluble and they have a hydrophobic rather than ahydrophilic character.

The developing agent may be a salt of an amine such as hexadecylamine,octadecylamine, eikosylamine, dokosylamine, dioctylamine,dioctadecylamine, N methyl N- octadecylamine,N,N-dimethyl-N-octadecylamine, 9-octadecenylamine, 3 (octadecyl)oxypropylamine. At least two cations derived from such amines must bepresent in a molecule of the salt in order that the salt shall be usefulin the present invention. The cations may be identical or different.

It has been found that as a rule the keeping quality of diazotypematerial according to the invention is better according as the cationsof the developing agent are derived from higher amines. However, inproportion as the molecular weight of the cations increases, thequantity of the developing agent which is required to obtain gooddevelopment increases, and in consequence the quantity of developingagent which has to be applied to the diazotype material per square metrealso increases.

Acids with which salts suitable as developing agents can be formed are,for instance, oxalic acid, phosphoric acid, metaphosphoric acid,phosphorous acid, diglycolic acid, maleic acid, dimethylmalonic acid andtartaric acid.

-' The salts suitable as developing agents can be used in the diazotypematerial according to the invention individually or mixed together.

The oxalates are very suitable developing agents on account of theexcellent keeping quality of the diazotype material made with them. Aparticularly suitable developing agent is di(octadecylammonium)oxalate.It is readily accessible, and diazotype material having excellentkeeping quality and yielding a strong colour upon development can bemade with it.

The acid-reacting compound present in the light-sensitive layer may beone of the acids commonly used in diazotype material, such as tartaricacid and citric acid. However, in-the diazotype material according tothe invention a moderately strong acid which is not volatile attemperatures below 100 C. is preferably used. Good results can beobtained with non-volatile acids having a dis- .sociation constantgreater than 10- Such acids are e.g.

oxalic. acid, phosphoric acid, maleic acid, sulfuric acid, and potassiumhydrogen sulfate.

Among these acids oxalic acid is outstanding. It stabilizes very welland the number of gram molecules of this acid which can be used in thediazotype material according to the invention can be greater than thatof acids such as phosphoric acid and maleic acid. When a comparativelylarge quantity of the last-mentioned acids is used and the colour of theazo-dyestutf formed upon development changes upon lowering of the pH,the shade of this azo-dyestutf may be adversely affected. This happens,for instance, with dyestuffs formed from 4-tert. aminobenzene diazocompounds and the important azocoupling component2,3-dihydroxynaphthalene-6-sulfonic acid, which are violet-red insteadof violet-blue at a pH below 3. Oxalic acid does not cause such a colourshift.

The diazotype material according to the invention can be made bytreating the surface of a support material in a conventional manner withan aqueous or non-aqueous sensitizing liquid in which the developingagent has been dispersed.

In order to be able to disperse the developing agent properly and toobtain a reasonably stable dispersion, it is necessary to use adispersing agent in the sensitizing liquid.

If the sensitizing liquid is an aqueous liquid, the dispersing agent tobe used may be a suitable surface-active substance, such as laurylalcohol sulfate and polyoxyethylene sorbitan monolaurate. Better resultsare obtained with hydrophilic film-forming organic binders which aresoluble in acid aqueous liquids, such. as methyl cellulose, hydroxyethylcellulose, hydroxypropyl cellulose, polyvinyl alcohol and gum arabic.

In aqueous liquids, a quantity of an aqueous dispersion of a syntheticresin, e.g. of polyvinyl acetate or poly-nbutylmethacrylate, may oftenalso be used as a dispersing agent with good results.

If the sensitizing liquid is a non-aqueous liquid, a hydrophobic binderwhich is soluble in the liquid, such as ethyl cellulose, polyvinylacetate and cellulose nitrate, can be used as a dispersing agent.

The diazotype material according to the invention may also, and oftenwith advantage, be made in two steps, e.g. by first coating a supportmaterial with a dispersion of the developing agent and drying, and nextsensitizing the dry layer thus formed with a solution of a diazocompound and drying the material again. (The azo-coupling component andthe acid-reacting compound may be incorporated in the dispersion or inthe sensitizing liquid, as desired.)

Whatever may be the method of manufacture, the diazotype materialaccording to the invention is preferably made as a one-layer material.However, it may also have a two-layer composition.

Diazotype materials according to the invention, made with abinder-containing dispersion, have better keeping quality and developmore rapidly than corresponding materials which have been made with abinder-free dispersion.

During the dispersion of the developing agent in water, a very stablefoam is often formed in the dispersion. This form can be veryinconvenient, eg when a layer is formed on a support material by meansof the dispersion. Curiously enough, during the preparation of suchaqueous dispersions of the developing agent only little foam, if any, isformed if cations derived from higher secondary amines, such asdi(octadecyl)amine, are present in the developing agent. Favourableresults are attained with developing agents in which about 30-60% of thecations are di(octadecyl) ammonium ions.

Diazo compounds which are eminently suitable for use in the diazotypematerial according to the invention are benzene diazo compounds with asecondary or tertiary amino group in para-position. Very suitableresults can be obtained with e.g.:

4-diazo-N,Ndimethylaniline, 4-diazo-N,N-diethylaniline,4-diazo-N-ethyl-N-2'-hydroxyethylaniline,4-diazo-3-ethoxy-N,N-diethylaniline,4-diazo-2-chloro-N,N-diethylaniline,4-diazo-N-methyl-N-cyclohexylaniline, 4-diazo-N-ethyl-N-benzylaniline,

4-diazo-5-chloro-2-(4'-ehlorophenoxy)-N,N-dimethylaniline,

4-diazo-5-chloro-2-ethoxy-N-methyl-N-benzylaniline,4-diazophenylmorpholine, 4-diazo-2,5-diethoxy-N-ethyl-N-benzylaniline,4-diazo-2,S-diethoxyphenylmorpholine, 4-diazo-2,5-di-n-butoxyphenylmorpholine, 4-diazo-2,S-dimethoxyphenylpiperidine,N-4-diazo-2,S-dipropoxyphenyl-N-methylpiperazine,N-4-diazo-2,5-diethoxyphenyl-N-acetylpiperazine, 4-diazo-diphenylamine,and 4-diazo-2-methoxy-N-methylaniline.

Suitable azo-coupling components are e.g.

2,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene-G-sulfonic acid,2,7-dihydroxynaphthalene-3,6-disulfonic acid,2-hyd-roxynaphthalene-3,6-disulfonic acid,l-benzoylamino-8-hydroxynaphthalene-4-sulfonic acid,

resorcinol, phloroglucinol, 7 hydroxy l, 2,4,5 naphthirnidazole, and3,5-dihydroxybenzene carbonarnide. Besides blue-coupling azo components,such as e.g. 2,3-dihydroxynaphthalene 6 sulfonic acid, so-calledyellowcoupling shading components may also be used in the diazotypematerial according to the invention in order to obtain ablack-developing material. Examples of such azocoupling components areaceoacetanilide, 3-hydroxyacet0- acetanilide, 4 hydroxyacetoacetanilide,3 carboxyacetoacetanilide, 4-carboxyacetoacetanilide, 3-methoxyphenol,diresorcyl sulfoxide, 2-acetoacetaminonaphtha1ene-6-sulfonic acid,2-acetoacetaminonaphthalene-7-sulfonic acid,2-acetoacetaminonaphthalene-8-sulfonic acid,Z-acetoacetarninonaphthalene-l-sulfonic acid,1-acetoacetaminonaphthalene-4-sulfonic acid,1-acetoacetaminonaphthalene-S- sulfonic acid.

The support of the diazotype material according to the invention may bepaper, tracing paper, linen, tracing linen, polyester film, celluloseacetate film, synthetic paper, or the like.

The following examples will serve to illustrate the invention. In theseexamples reference is made to certain compounds by their trade names. Ofthese the following are registered trademarks: Tylose, Rhodoviol, Tween,Vinnapas, Plextol, Duponol.

Example I thus formed is sucked off, and the residue is washedwithethanol. After drying, the residue weighs 832 g. Thedi(octadecylammonium)oxalate thus prepared melts at 204-205" C.

A. A dispersion containing:

Di(octadecylammonium)oxalate g 100 Ethanol (96%) ml 100 Water ml 1000 isprepared, and this dispersion is ground for 20 hours in a ball-mill.

B. A solution of:

4-morpholinobenzene diazonium chloride, zinc chloride double salt 20Sodium salt of 2,3-dihydroxynaphthalene-6-sulfonic in 1000 ml. of wateris prepared.

Then Dispersion A g 550 Solution B ml 200 Water ml 250 are addedtogether and the mixture is stirred until it is homogeneous.

White base-paper of weight g./m. and suitable for the diazotaype processis sensitized with the mixture in such a way that, after drying, auniform layer of about 7 g./rn. is present on it. From the diazotypepaper thus formed a sheet is cut, which is marked with the letter C.

A sheet of the same white base-paper is sensitized with the solutiondescribed in Example 7 of British patent specification No. 907,724, insuch a way that, after drying, the diazotype paper thus obtainer, whichis marked with the letter D, has equal light-sensitivity to thediazotype paper C.

A strip of the two sheets is kept for 24 hours in a room with atemperature of 35 C. and a relative humidity of 75%.

After these 24 hours the strip D shows an intensive blue colorthroughout its surface, Whilst the strip C is practically as yellow asbefore. The two strips are exposed until all the diazo compound presenton them has bleached out. 'Now, strip C shows a slight, somewhat violetfogginess. Strip D, on the contrary, shows an intensive blue color. Thedifference in keeping quality appears from the difference in the extentof premature azo-dyestuff formation, and in this respect the diazotypematerial according to the invention is greatly superior.

The remaining parts of the diazotype papers C and D are imagewiseexposed in fresh condition underneath a letter typed on thin paper untilunderneath the white portions of the letter all the diazo compound hasbleached out, and are then guided over a rotating metal cylinder with asurface temperature of about C., their lightsensitive sides being incontact with the cylinder surface for 10 seconds.

The copy on sheet D shows a violet-blue image on a white background, thecopy on sheet C a violet image on a white background.

Example II A. A dispersion containing: Di(octadecylammonium)oxalate g 80Methyl cellulose of the type Tylose MH 200 K g 20 Water ml 1000 isprepared, and this dispersion is ground for 20 hours in a ball-mill.

By solution of:

Grams 4-morpholino-2,S-diethoxybenzene diazonium chloare added together,and the liquid is stirred until it is homogeneous.

A sheet of white base-paper of weight 80 g./m. and suitable for thediazotype process is sensitized with this liquid and then dried.

The sensitized sheet is imagewise exposed as described in Example I anddeveloped by guiding it over a rotating metal cylinder with a surfacetemperature 'of about 150 C., so that the light-sensitive side is incontact with the cylinder surface for 8 seconds.

The copy shows a strong blue image on a bright white background.

Example 111 (1) 100 g. of di(octadecylammonium)oxalate is dispersed in asolution of 15 g. of gum arabic in 500 ml. of water and this dispersionis ground for 20 hours in a ball-mill.

(2) A solution containing:

is prepared.

(3) The dispersion prepared as decribed under (1) is mixed with thesolution prepared as described under (2); to the liquid thus obtained isadded 18 g. of oxalic acid, and the total volume of the liquid is madeup to 1 litre.

With the liquid prepared as described above, white basepaper of weight80 g./m. and suitable for the diazotype process is treated, so that aliquid layer of about 50 g./m. is applied on one side of it, then it isdried.

The side of the paper thus treated is sensitized with a solution of 14g. of 4-morpholino-2,5-diethoxybenzene diazonium sulfate, 1 g. ofpolyoxyethylene sorbitan monolaurate (Tween 20) in 1000 ml. of Water anddried.

A sheet of the diazotype material thus made is imagewise exposedunderneath a letter typed on translucent paper of about 50 g./m. untilunderneath the white portions of the letter nearly all the diazocompound has bleached out.

The imagewise exposed sheet of diazotype material is subsequentlydeveloped by guiding it over a heated rotating roller with a surfacetemperature of about 150 C., so that the back of the sheet is in contactwith the roller surface for 8 seconds.

The copy shows a strong black image.

Example IV A dispersion containing:

Di(octadecylammonium)oxalate g 400 Polyoxyethylene sorbitan monolaurate(Tween 20) g 40 Water "ml.-- 1000 is prepared, and this dispersion isground for 20 hours in a ball-mill. The dispersion is filtered, thedispersed particles remaining behind as a residue on the filter. Thisresidue is dried.

(a) To a sensitizing liquid containing:

4-diethylaminobenzene diazonium chloride, zinc chloride double salt g 6Sodium salt of 2-acetoacetaminonaphthalene-6-sulfonic acid g Oxalic acidg 22 Aqueous polyvinyl acetate dispersion Vinnapas H.60 ml 100 Water-..ml 800 copy shows a yellow image on a translucent colour-freebackground. It is very suitable as an intermediate original for themaking of further copies on diazotype material.

(b) To a sensitizing liquid containing: 4-morph0lino-2,5-diethoxybenzenediazonium chloride, zinc chloride double salt g 10 Sodium salt of2,3-dihydroxynaphthalene-6-sulfonic acid g 25 Tartaric acid g 40 Aqueouspoly-n-butylmethacrylate dispersion Plextol P2n ml 400 Water ml 500Example V 63 g. of oxalicacid is dissolved in 10,000 ml. of ethanol(96%). This solution is heated to 60 C. and 135 g. of octadecylamine isadded gradually.

The liquid is then heated to its boiling point, after which thefollowing solution, which has been heated to about 60 C., is addedgradually: 256 g. of dioctadecylamine in 5000 ml. of ethanol (96%).After this solution has been completely added to the first-mentionedsolution, the liquid thus obtained is heated for /2 hour to 75 C. Afterthe liquid has been cooled to room temperature, the precipitate issucked off and washed with ethanol (96% The product thus obtained meltsat l53-l56 C.

In a solution of 50 g. of ethyl cellulose (low viscosity) in 1000 ml. ofethanol (96%) 120 g. of the product prepared as described above isdispersed. The dispersion thus obtained is ground for 20 hours in aball-mill.

After the grinding operation, a layer of about 10 g./m. dry weight, isformed, on sized natural tracing paper of weight g./m. with the grounddispersion.

On this layer a light-sensitive layer is applied by spreading on it aliquid containing:

A sheet of the transparent diazotype paper thus obtained is imagewiseexposed and developed as described in Example II.

The copy shows a blue image on a transparent background.

Example VI To 2000 ml. of ethanol (96%) is added 50 m1. of phosphoricacid by weight). This liquid is heated to 50 C., after which 100 g. ofoctadecylamine is added gradually.

The liquid is then heated to its boiling point.. Upon coolingoctadecylammonium hydrogen phosphate crystallizes out. The precipitateis filteredand recrystallized from ethanol (96%). A white crystallinepowder is obtained.

60.6 g. of this powder is dissolved in 1000 ml. of ethanol (96%). Thissolution is heated to its boiling point, after which a hot solution of172 g. of dioctadecylamine in 10,000 ml. of ethanol (96%) is addedgradually. The liquid is cooled and the precipitate thus formed issucked 0E.

9 The precipitate is washed with ethanol (96%). The product thusobtained is crystalline and melts at 98- 106 C.

A dispersion containing Phosphate prepared as described above g 200 Gumarabic g 30 Water ml 1000 is prepared, and the dispersion is ground for20 hours in a ball-mill.

' To 500 ml. of this dispersion are added:

Polyvinyli alcohol Rhodoviol 30/20 M g 10 Polyvinyl alcohol Rhodoviol4/200 P g 30 Phosphoric acid (85% by weight) ml 20 Water ml 450 and withthe liquid thus obtained white base-paper of 80 g./m. for the diazotypeprocess is treated on one side. After drying, the side thus treated issensitized with a liquid containing:

4-p-tolylthio-2,5-diethoxybenzene diazonium chloand dried again.

A sheet of the diazotype paper thus obtained is imagewise exposed anddeveloped as described in Example II. The copy shows a purple image on awhite background.

Example VII 100 g. of octadecylamine is dissolved in 4000 ml. of ethanol(96% This dispersion is heated to 50 C. and, while stirring, such aquantity of a solution of 28 g. of tartaric acid in 280 ml. of ethanolis added gradually until the reaction mixture has a neutral reaction tolitmus.

The reaction mixture is cooled to C. and the precipitate thus formed issucked off. The residue is washed with ethanol (96%) and dried. The dryresidue weighs 115.5 g.

The melting point of the tartrate thus prepared is 108 C.

Di(octadecylammonium)diglycolate is prepared in an analogous way. Duringthe preparation of this product, in the above formula the 28 g. oftartaric acid is replaced by 26 g. of diglycolic acid. In this case theresidue weighs 110 g. The di(octadecylammonium)diglycolate thus obtainedmelts at 87-91" C.

Di(octadecylammonium)maleate is also prepared in an analogous way. Forthat purpose in the given formula the 28 g. of tartaric acid is replacedby 26 g. of maleic acid. The residue weighs 103.5 g. Thedi(octadecylammonium)maleate melts at 99l02 C.

To 1000 ml. portions of a solution of 200 g. of methyl cellulose TyloseMH 20 K in 10,000 ml. of water are added successively: (a) 100' g. ofdi(octadecylammonium)tratrate and 15 g. of oxalic acid; (b) 100 g. ofdi- (octadecylammonium)diglycolate and 15 g. of diglycolic acid; (0) 100g. of di(octadecylammonium)maleate and g. of maleic acid.

The three dispersions are ground for 29 hours in a ballmill.

Sheets of white base-paper of weight 80 g./m. and suitable for thediazotype process are then coated with each of the dispersions on oneside with a layer having a weight of 6 to 7 g./m. after drying.

The sides of the three sheets thus treated are sensitized with asolution of G; 4-morpholino-2,S-diethoxybenzene diazonium sulfate 20 Thesodium salt of 2,3-dihydroxynaphthalene-6-sultonic acid 40 Oxalic acid0.4

Technical lauryl alcohol sulfate Duponol ME 3 in 1000 ml. of water anddried.

The sheets of diazotype paper are imagewise exposed and developed asdescribed in Example II.

The copies show a violet blue image on a white background.

Example VIII 141.5 g. of N-octadecyl-N-methylamine is dissolved in 1500'ml. of ethanol (96%), and the solution is heated to 50 C. Whilestirring, such a quantity of a solution of 25 g. of oxalic acid in 500ml. of ethanol (96%) is added gradually to the solution until thereaction mixture has a neutral reaction to litmus.

The reaction mixture is cooled to 0 C. and the precipitate thus formedis sucked oil. The residue is washed with ethanol and dried. The dryresidue weighs 105 g. The di(N-methyl-N-octadecylammonium)oxalate thusprepared melts at 145 C. 240 g. of N,N-dimethyl-N-octadecylamine isdissolved in 1500 ml. of ethanol (96% While stirring, a solution of 50.4g. of oxalic acid in 500 ml. of ethanol (96%) is added gradually to thissolution. The reaction mixture is diluted with ether to 8000 ml. A whiteprecipitate is thus formed. The precipitate is sucked off, and theresidue is washed with ether and dried. The

dried residue weighs 102 g.

The di N,N-dimethyl-N-octadecylammonium) oxalate thus prepared melts at203204 C. with decomposition.

The following dispersions are prepared:

Di(N-octadecyl-N-methylammonium) oxalate g Methyl cellulose Tylose MH 20K g 20 Oxalic acid g 15 Water ml.. 1000' Oxalate prepared according tothe formula in Example V g 100 Methyl cellulose Tylose MH 20 K g 20Oxalic acid g 15 Water ml 1000 Di(N,N dimethylN-octadecylammonium)oxalate g" 100 Methyl cellulose Tylose ME 20 K a g20 Oxalic acid g 15 Water rnl 1000 The three dispersions are ground for20 hours in a ballmill.

Sheets of opaque linen for the diazotype process are then coated witheach of the dispersions in such a way that the dry layer has a weight ofabout 6 g./m.

The layer of each sheet is sensitized with a solution of 4 N methylN-benzylamino-2-chloro-5-methoxybenzene diazonium chloride, zincchloride double salt 10 Sodium salt of2,7-dihydroxynaphthalene-3,6-disulfonic acid 20 Oxalic acid 0.4

in 1000 ml. of water and dried.

The three sheets of diazotype linen are imagewise ex posed and developedas described in Example II.

The copies show a violet image on a white background.

Example D( To the dispersion (b) of Example VIII is added 20 g. of thesodium salt of 2,3-dihydroxynaphthalene-6-sulfonic acid. The dispersionis then ground, and a layer having a dry weight of about 8-9 g./m. isformed with it on white base paper of weight 80 g./m. and suitable forthe diazotype process.

This layer is sensitized with a solution which contains g. of4-phenylaminobenzene diazonium sulfate in 1000 ml. of water, and hasbeen brought to pH 3 with oxalic acid. After sensitization the layer isdried.

A sheet of the diazotype paper thus obtained is image- Wise exposed anddeveloped as described in Example II.

The copy shows a blue image on a white background.

Example X Tartrate prepared as described above g 100 Methyl celluloseTylose MH K g Phosphoric acid (89% by weight) ml 7 Water ml 1000 isprepared, and this dispersion is ground for 20' hours in a ball-mill.

With the ground dispersion a layer having a dry weight of 10-11 g./m. isformed on white base paper of weight 80 g./m. suitable for the diazotypeprocess.

This layer is sensitized with a solution of:

G. 4-morpholino-2,S-diethoxybenzene diazonium sulfate 20 Sodium salt of2,3-dihydroxynaphthalene-6-sulfonic acid 40 Oxalic acid 0.5 Technicallauryl alcohol sulfate Duponol ME 3 in 1000 ml. of water and dried.

A sheet of the diazotype paper is imagewise exposed and developed asdescribed in Example II.

The copy shows a blue image on a white background.

What is claimed is:

1. Heat-developable diazotype material which comprises a diazo compound,an azo-coupling component, an acid-reacting compound, and a developingagentwhich, upon heating, is able to neutralize an acid, the variouscomponents being distributed over at most two layers of the material andthe developing agent being a water-insoluble salt of a polybasic acidhaving a first dissociation constant between 7 10- and 1 10- and analiphatic amine of the general formula in which R is an aliphatichydrocarbon radical of at least 8 carbon atoms, and R and R stand for ahydrogen atom or an aliphatic hydrocarbon radical, while R R and Rtogether carry at least 16 carbon atoms, the said salt containing atleast two cations formed from an amine of the said formula.

2. Heat-developable diazotype material according to claim 1 wherein thedeveolping agent is a salt of oxalic acid.

3. Heat-developable diazotype material according .to

claim 2, wherein the developing agent is di(octadecylammonium) oxalate.

4. Heat-developable diazotype material according to claim 1, wherein theacid-reacting compound is oxalic acid.

5. Heat-developable diazotype material according to claim 1, whichcontains, in addition, a water-soluble hydrophilic binder for some orall of the said components.

6. Heat-developable diazotype material according to claim Lwherein30-60% of the cations present in the developing agent aredi(octadecyl)amrnonium ions.

7. Heat-developable diazotype material according to claim 1, whichcomprises a water-soluble hydrophilic organic binder for some or all ofthe said constitutuents,

and wherein the acid-reacting compound comprises oxalic acid and thedeveloping agent comprises di(octadecylammoniurn)oxalate.

8. Heat-developable diazotype material according to claim 1, comprisinga flexible sheet having formed thereon a light-sensitive layercontaining the said constituents and also containing polyvinyl alcoholand polyvinyl pyrrolidone as binders.

References Cited UNITED STATES PATENTS 3,255,007 6/1966 Kosar 96913,284,201 11/1966 Meijs et al. 96-91 X 3,316,092 4/1967 Klimkowski etal. 96-91 FOREIGN PATENTS 907,724 10/ 1962 Great Britain.

NORMAN G. TORCHIN, Primary Examiner.

C. BOWERS, Assistant Examier.

- US. Cl. X.R. 9649, 91

